Exercise and Air Pollution

Continued...

It has long been known that high levels of ozone exposure are dangerous to health, and levels of ozone are monitored in most metropolitan areas. In 1979, the Federal Health Standard for "good air quality" was set at .12 parts of ozone per 1 million parts of air for one hour (abbreviated as ppm/hour). The Canadian level is set at .08 ppm/hour, and experts in the U.S. have seriously questioned the margin of safety provided by the national clean air standard.

A Stage One ozone episode occurs at an ozone concentration of .20 ppm/hour and is defined as "air unhealthy for sensitive people." The elderly, young children and people with underlying heart and lung diseases are usually in the category of "sensitive people." So are exercising healthy adults. However, new evidence indicates that lung function is impaired in exercising healthy adults when concentrations of ozone are at or below the Federal Clean Air Standard of .12 ppm/hour.

How much ozone enters your lungs depends mainly on how much is in the air, but the intensity and duration of your workout are also factors. If you run at an easy pace for 20 minutes, and a friend bicycles at top speed for 40 minutes in the same air, your exposure will be less than hers.

People vary in their sensitivity to ozone. The limited studies to date suggest that "impaired performance may begin at .12 ppm/hour and is very likely at .20 ppm for most athletes exercising heavily for one or more hours," says Dr. Henry Gong, a researcher at UCLA.

Healthy lungs seem to be able to adapt to smog and perhaps protect themselves from its effects. After two to seven days of ozone exposure, most people have less severe symptoms and less respiratory difficulty. Smog-sensitive people may take a longer time to adapt.

Contrary to popular belief, high doses of vitamin E (800 to 1600 I.U.) have not been shown to protect against the effects of air pollution. Doses of 1 gram of Vitamin C a day may lessen some symptoms in some people exposed to very high levels of ozone (.30 ppm for 2 hours). However, this amount of Vitamin C can cause gastrointestinal upset.

What are the long-term health effects of exposure to polluted air?

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Table of Contents

Foreword: Billie Jean King

Comments by Barb Harris
Editor in Chief,
Shape Magazine

General Health
Nutrition
Exercise
Common Medical Problems
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Emergency!
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Eating Disorders
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Environmental Health
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